A device for monitoring the access to the cardiovascular system of a patient undergoing an extracorporeal treatment of blood in a machine (1) comprising a treatment device (4) and an extracorporeal circuit (2), comprises: a voltage generator (16) for generating a potential difference between a part of the machine (1) and a first point (B) of a venous branch (8) of the extracorporeal circuit (2), connecting the patient to the treatment device (4); a detector (17) for detecting the value (dV) of a quantity that correlates with the electric current along at least one section (10a; 10b; 10c) of the venous branch (10) between the first point (B) and a venous needle (13) fitted at the end of the venous branch (8) and inserted in the vascular system of the patient (P); calculating means (15) for comparing the detected value (dV) with a reference range (I).
|
12. A device for monitoring a cardiovascular access during an extracorporeal blood treatment comprising:
a conductive connection arranged between a first passage point of an arterial branch of an extracorporeal blood circuit, and a second passage point of a venous branch of the extracorporeal blood circuit;
a voltage generator circuit configured to generate a potential difference between said first and second passage points when the extracorporeal blood circuit is connected to a patient through an arterial needle and a venous needle;
a detector circuit configured to detect a value of a quantity corresponding to an electric current along at least one section of the extracorporeal circuit, said at least one section of the extracorporeal circuit comprising:
a portion of the venous branch between the second passage point and the venous needle;
a portion of the arterial branch between the arterial needle and the first passage point; and
the conductive connection; and
a comparator circuit configured to compare the value to a reference range.
1. A method of monitoring a cardiovascular access during an extracorporeal blood treatment, comprising the steps of:
providing an extracorporeal blood circuit comprising an arterial branch and a venous branch, the arterial branch connecting an arterial needle inserted into a patient to an inlet of a blood treatment device, the venous branch connecting an outlet of the blood treatment device to a venous needle inserted into a patient;
providing a conductive connection between the arterial branch and the venous branch, said conductive connection having first and second connection locations, wherein said first connection location is located upstream of the blood treatment device and said second connection location is located downstream of said blood treatment device;
circulating blood in the extracorporeal blood circuit;
generating a potential difference between the arterial branch and the venous branch;
detecting a value of a quantity corresponding to an electric current along at least one portion of the venous branch, said at least one portion being between the conductive connection and the venous needle; and
comparing the detected value to a reference range.
2. A method according to
3. A method according to
4. A method according to
5. A method according to
6. A method according to
7. A method according to
8. A method according to
9. A method in accordance with
10. A method according to
11. A method according to
13. A device according to
14. A device according to
15. A device according to
16. A device according to
17. A device according to
18. A device according to
19. A device according to
20. A device according to
21. A device according to
24. A device according to
25. A device according to
26. A device according to
27. A device according to
|
The present invention relates to a method and a device for monitoring the access to the cardiovascular system of a patient undergoing an extracorporeal treatment of blood.
The invention is useful in any kind of treatment in which blood is continuously withdrawn from a patient, circulated and treated in a treatment device, and returned, once treated, to the patient. Hemodialysis, hemofiltration, apheresis and plasmapheresis are examples of such treatment.
For the sake of clarity, the invention will be described hereunder in relation to a specific treatment, hemodialysis, to which however it is not limited as will readily appear to the persons skilled in the art.
A dialysis machine generally comprises.
In use, the blood of the patient and the dialysis liquid are respectively circulated in the first and the second compartments, generally in counterflow.
During a dialysis treatment, undesirable substances (by-products of the metabolism, such as urea, creatinine, etc.) contained in the blood migrate across the semipermeable membrane from the blood compartment to the dialysis liquid compartment by diffusion (dialysis phenomenon, strictly speaking) and also generally by convection, a fraction of plasma water being usually filtered during the treatment so that the patient looses a few kilograms (so-called “weight loss”) corresponding to an excess of water accumulated in the body between two treatment sessions.
Each branch of the extracorporeal circuit is fitted with a needle (respectively, arterial needle and venous needle), by means of which the extracorporeal circuit is connected to the patient: just before starting the treatment, the arterial needle and the venous needle are inserted in the fistula of the patient (portion of a vein surgically connected to an artery) for respectively collecting the blood to be treated and returning the treated blood to the patient's cardiovascular system.
Disconnection of one of the aforementioned needles from the fistula causes interruption of access to the patient's cardiovascular system. Disconnection of the venous needle, if not detected in time, has particularly serious consequences, as it can cause exsanguination of the patient. For this reason there have been various attempts to provide methods capable of detecting disconnection of the needles, and especially of the venous needle.
One of these methods, which is based on the electrical conductivity of the blood, is described in WO 99/12588. According to this method, the extracorporeal circuit and the patient's cardiovascular system are subjected to an electric current, and changes in the current that are caused by the disconnection of one of the needles or both of the needles is detected, by means of measuring instruments arranged along the extracorporeal circuit. The measuring instrument used are inductive couplers, i.e. coils arranged at predetermined locations along the extracorporeal blood circuit.
The method described above has various drawbacks. In particular, although valid from the theoretical standpoint, this method is not able to provide satisfactory results from the practical standpoint, because the high electrical impedance caused by the peristaltic pump, which in fact interrupts the continuity of blood flow, necessitates operating with relatively high currents in order to make use of the scant conductivity of the materials of which the extracorporeal circuit, the dialyzer, the hose of the peristaltic pump and the bubble trap are made (PVC, polycarbonate). The use of relatively high currents is certainly not advisable in a machine connected to a patient and even if they were used, it would not be possible to transmit these high currents by means of an inductive coupler which, among other things, also generates parasitic currents which disturb the measurement. In some dialysis machines the bubble trap also represents a high impedance of the same order of magnitude as the peristaltic pump, and thus makes one of the drawbacks previously described even more acute.
Therefore, in view of the fact that it is advisable to operate with relatively low currents and that the impedance of the peristaltic pump, and in the majority of cases, of the bubble trap, is high, it follows that disconnection of one of the needles causes only slight changes in current, such as could be confused with the background noise of the measuring instrument.
Furthermore, this method does not take into account that the patient might be connected to earth and that the dialyzer itself is in fact connected to earth, since the dialysis fluid circuit is connected to earth in accordance with the provisions of the safety standards relating to dialysis machines.
The aim of the present invention is to provide a method that obviates the drawbacks of the prior art.
According to the present invention, a method is provided for monitoring the access to the cardiovascular system of a patient undergoing an extracorporeal treatment of blood in a machine comprising a treatment device and an extracorporeal circuit having an arterial branch and a venous branch, the arterial branch having a first and fitted with an arterial needle to be inserted in the vascular system of the patient and a second end connected to an inlet of the treatment device, and the venous branch having a first end connected to an outlet of the treatment device and a second end fitted with an venous needle to be inserted in the vascular system of the patient, the method being characterized in that it comprises the steps of:
The present invention relates, in addition, to a monitoring device.
According to the present invention, a device is provided for monitoring the access to the cardiovascular system of a patient undergoing an extracorporeal treatment of blood in a machine comprising a treatment device and an extracorporeal circuit having an arterial branch and a venous branch, the arterial branch having a first end fitted with an arterial needle to be inserted in the vascular system of the patient and a second end connected to an inlet of the treatment device, and the venous branch having a first end connected to an outlet of the treatment device and a second end fitted with an venous needle to be inserted in the vascular system of the patient, the device being characterized in that it comprises:
The invention will now be described, with respect to the appended drawings, in which:
In
The extracorporeal blood circuit 2 comprises, in addition to the compartment 5 of dialyzer 4, an arterial branch 8, along which a peristaltic pump 9 is arranged, supplying a blood flow Qb, and a venous branch 10, to which a bubble trap 11 is connected. Arterial branch 8 has a needle 12 which, in use, is inserted in a fistula of patient P to collect blood from the cardiovascular system of the patient P, while venous branch 10 has a venous needle 13 which, in use, is inserted in the fistula for returning the treated blood to the cardiovascular system of patient P. Arterial and venous branches 8 and 10 are tubes made of a plastic material, generally PVC, as well as bubble trap 11. Dialyzer 4 is also made of plastic material, the housing of it generally of polycarbonate.
In
The impedances of the other compartments of extracorporeal circuit 2 are negligible with respect to the values of impedance Z1. To evaluate the operation of device 14, it is necessary to bear in mind that the dialyzer 4 is connected to earth via the dialysis fluid circuit 3 and that the patient P may be connected to earth (R=0) or insulated (R=infinity) or in a situation intermediate between the two preceding limiting situations. These distinctions are important as it would be difficult to prevent the patient P from moving, for example resting a foot on the floor or placing a hand on the bedhead of an uninsulated bed, thus altering the configuration of the possible electric circuits defined by the machine 1, the patient P, and device 14.
In
Capacitive couplers 21, 22, 25 and 26 are made with respective metal tubes 27, which are connected to the respective conductors 19, 20, 23 and 24 and are arranged around portions of the respective PVC tubes. From the electrical standpoint, tube 27 defines a first plate of a capacitor, the PVC tube defines the dielectric, and the blood inside the PVC tube defines the second plate.
Capacitive coupler 21 is arranged on arterial branch 8 at a point A between the arterial needle 12 and the peristaltic pump 9, while capacitive coupling 22 is arranged on the arterial branch 10 at point B between bubble trap 11 and needle 13. Detector 17 is connected to venous branch 10 at points C and D, both of which are between point B and the venous needle 13 and define the end of section 10a.
When the patient is insulated (R infinite) and impedance Z2 is high, the operation of the monitoring device 14 according to the invention is as follows: the blood being circulated in the extracorporeal circuit 2 in the direction indicated by the arrows in
When one of the needles 12 and 13 accidentally becomes disconnected from the fistula, the detector 17 detects the cancellation of the voltage drop dV in section 10a, and the control unit 15 emits signals S, G and T for stopping the peristaltic pump 9, closing the clamp 18, and emitting an alarm signal.
The monitoring device 14 is particularly advantageous because it by-passes the impedance Z1 and Z2, and the dialyzer 4 which is connected to earth. Therefore it is possible to work with relatively low currents since disconnection of one of the needles 12 and 13 represents an appreciable change in the current along a circuit comprising a portion of the arterial branch 8 and a portion of the venous branch 10, the conductors 19 and 20 and the cardiovascular system of the patient P.
When the patient P is connected to earth (R=0), if the venous needle 13 becomes disconnected, there is no current flowing through the venous branch 10 and therefore detector 17 detects a voltage drop equal to zero as is the case when patient P is insulated. If the arterial needle 12 becomes disconnected, there is a voltage drop in section 10a, which is a function of the impedance Z1 of the peristaltic pump and is therefore significant owing to the high value of impedance Z1.
When Z2 is negligible, disconnection of venous needle 13 is detected both when the patient is insulated (R infinite) and when he is connected to earth (R=0), as preferential flow of current occurs along the portion of extracorporeal circuit 2 on the side of patient P.
In the embodiment of
When the patient P is insulated (R infinite) and Z2 is high, the current circulates through conductors 19 and 20, a portion of the venous branch 10 and a portion of the arterial branch 8. Disconnection of one of the needles 12 and 13 has the effect that the voltage drop is cancelled along the section 10b and the patient P.
When the patient P is connected to earth (R=0), a disconnection of the venous needle 13 causes the cancellation of the voltage drop as in the proceding case, whereas when the arterial needle 12 is disconnected, the voltage drop becomes a function of the impedance Z1 as in the preceding case.
When Z2 is negligible, the considerations relating to the variant in
According to a variant that is not shown, again the capacitive coupler 26 is omitted and is replaced with a conductive bracelet, not shown, connected directly to one wrist of the patient P. The operation of the said variant that is not shown does not differ substantially from the variant in FIG. 2.
According to the variant in
In use, when the patient P is insulated (R infinite) and the impedance Z2 is high, the value dV of voltage drop along section 10c of the venous branch, section 8c of the arterial branch 8, and the cardiovascular system of the patient P is detected. Section 10c is between point C and arterial needle 13, whereas section 8c is between point F and venous needle 12. Disconnection of one of the needles 12 and 13 causes cancellation of the voltage drop.
When the patient P is connected to earth (R=0), a disconnection of the venous needle 13 causes the cancellation of the voltage drop, whereas a disconnection of the arterial needle 12 does not cause any appreciable change in the voltage drop dV.
When the impedance Z2 is negligible, a low current will pass along section 10c, however section 10c along which the voltage drop dV is determined is relatively long and therefore a detection thereof is significant.
In practice, all the variants of the monitoring device 14 described with reference to the
Rossi, Ivan, Giacomelli, Sara, Canini, Enrico
Patent | Priority | Assignee | Title |
10155082, | Apr 10 2002 | Baxter International Inc; BAXTER HEALTHCARE S A | Enhanced signal detection for access disconnection systems |
10463778, | Feb 09 2007 | Baxter International Inc.; Baxter Healthcare S.A. | Blood treatment machine having electrical heartbeat analysis |
10507279, | Dec 28 2009 | Gambro Lundia AB | Controlling an apparatus for fluid transfer to and/or from a subject |
7060047, | Jun 15 2001 | Gambro Lundia AB | Method and device for sensing the detachment of the venous needle from a patient during an extracorporeal blood treatment in a dialysis machine |
7107837, | Jan 22 2002 | BAXTER INTERNATIONAL, INC ; BAXTER HEALTHCARE S A | Capacitance fluid volume measurement |
7537687, | Oct 15 2004 | NIKKISO CO., LTD.; NIKKISO CO , LTD | Hemodialysis device |
7682328, | Apr 10 2002 | Baxter International Inc. | Access disconnection systems and methods |
7758555, | Sep 19 2006 | SOLVENTUM INTELLECTUAL PROPERTIES COMPANY | Reduced pressure treatment system having blockage clearing and dual-zone pressure protection capabilities |
7927319, | Feb 20 2007 | SOLVENTUM INTELLECTUAL PROPERTIES COMPANY | System and method for distinguishing leaks from a disengaged canister condition in a reduced pressure treatment system |
8114043, | Jul 25 2008 | Baxter International Inc.; Baxter Healthcare S.A. | Electromagnetic induction access disconnect sensor |
8137300, | Apr 10 2002 | Baxter International Inc.; Baxter Healthcare S.A. | Access disconnection systems and methods using conductive contacts |
8152751, | Feb 09 2007 | Baxter International Inc; BAXTER HEALTHCARE S A | Acoustic access disconnection systems and methods |
8180443, | Sep 12 2006 | Fresenius Medical Care Deutschland GmbH | Device and method for monitoring a patient access, in particular a vascular access in extracorporeal blood treatment |
8298152, | Sep 08 2006 | Fresenius Medical Care Deutschland GmbH | Device and method for monitoring an access to a patient, in particular a vascular access in extracorporeal blood treatment |
8328776, | Sep 19 2006 | SOLVENTUM INTELLECTUAL PROPERTIES COMPANY | Reduced pressure treatment system having blockage clearing and dual-zone pressure protection capabilities |
8366690, | Sep 19 2006 | SOLVENTUM INTELLECTUAL PROPERTIES COMPANY | System and method for determining a fill status of a canister of fluid in a reduced pressure treatment system |
8366691, | Aug 08 2008 | SOLVENTUM INTELLECTUAL PROPERTIES COMPANY | Reduced-pressure treatment systems with reservoir control |
8376978, | Feb 09 2007 | Baxter International Inc; BAXTER HEALTHCARE S A | Optical access disconnection systems and methods |
8409170, | Feb 09 2007 | SOLVENTUM INTELLECTUAL PROPERTIES COMPANY | System and method for managing reduced pressure at a tissue site |
8529490, | Apr 10 2002 | Baxter International Inc.; Baxter Healthcare S.A. | Systems and methods for dialysis access disconnection |
8603020, | Feb 09 2007 | Baxter International Inc.; Baxter Healthcare S.A. | Ultrasound access disconnection systems and methods |
8632486, | Jul 25 2008 | Baxter International Inc.; Baxter Healthcare S.A. | Electromagnetic induction access disconnect systems |
8708946, | Apr 10 2002 | Baxter International Inc.; Baxter Healthcare S.A. | Access disconnection systems using conductive contacts |
8795217, | Feb 09 2007 | Baxter International Inc.; Baxter Healthcare S.A. | Acoustic access disconnection systems and methods |
8801646, | Apr 10 2002 | Baxter International Inc.; Baxter Healthcare S.A. | Access disconnection systems with arterial and venous line conductive pathway |
8827967, | Feb 20 2007 | SOLVENTUM INTELLECTUAL PROPERTIES COMPANY | System and method for distinguishing leaks from a disengaged canister condition in a reduced pressure treatment system |
8920355, | Feb 09 2007 | Baxter International Inc.; Baxter Healthcare S.A. | Acoustic access disconnection systems and methods |
8920356, | Apr 10 2002 | Baxter International Inc.; Baxter Healthcare S.A. | Conductive polymer materials and applications thereof including monitoring and providing effective therapy |
9039648, | Nov 05 2003 | Baxter International Inc.; Baxter Healthcare S.A. | Dialysis system with enhanced features |
9089654, | Feb 09 2007 | Baxter International Inc.; Baxter Healthcare S.A. | Acoustic access disconnection systems and methods |
9138528, | Feb 09 2007 | Baxter International Inc.; Baxter Healthcare S.A. | Acoustic access disconnection systems and methods |
9138536, | Apr 01 2008 | Gambro Lundia AB | Apparatus and a method for monitoring a vascular access |
9289545, | Dec 28 2009 | Gambro Lundia AB | Controlling an apparatus for fluid transfer to and/or from a subject |
9352078, | Feb 09 2007 | Baxter International Inc.; Baxter Healthcare S.A. | Electrical heartbeat access disconnection systems |
9550020, | Nov 05 2003 | Baxter International Inc.; BAXTER HEALTHCARE SA | Dialysis system with a varying rate ultrafiltration profile |
9833556, | Dec 28 2009 | Gambro Lundia AB | Controlling an apparatus for fluid transfer to and/or from a subject |
9950105, | Feb 09 2007 | Baxter International Inc.; BAXTER HEALTHCARE SA | Blood treatment and electrical blood leak detection device therefore |
Patent | Priority | Assignee | Title |
3867688, | |||
4661093, | Jun 11 1983 | Walter, Beck; Margrit, Werner | Method for aspirating secreted fluids from a wound |
5510717, | |||
5644240, | Sep 30 1992 | GAMBRO RENAL PRODUCTS, INC | Differential conductivity hemodynamic monitor |
5685240, | Nov 13 1995 | RILEY POWER INC | Variable orifice plate for coal pipes |
6663585, | Sep 06 1997 | Fresenius Medical Care Deutschland GmbH | Method and device for monitoring vessel access during extracorporeal blood treatment |
FR2067572, | |||
WO9912588, | |||
WO9924145, |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Dec 22 2000 | Gambro Hospal | (assignment on the face of the patent) | / | |||
Oct 08 2001 | CANINI, ENRICO | GAMBRO HOSPAL SCHWEIZ AG | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 012396 | /0609 | |
Oct 09 2001 | ROSSI, IVAN | GAMBRO HOSPAL SCHWEIZ AG | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 012396 | /0609 | |
Oct 10 2001 | GIACOMELLI, SARA | GAMBRO HOSPAL SCHWEIZ AG | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 012396 | /0609 | |
Nov 30 2006 | GAMBRO HOSPAL SCHWEIZ AG | CITICORP TRUSTEE COMPANY LIMITED | SECURITY AGREEMENT | 018573 | /0281 | |
Dec 07 2011 | CITICORP TRUSTEE COMPANY LIMITED, AS SECURITY AGENT | GAMBRO HOSPAL SCHWEIZ AG | RELEASE OF SECURITY INTEREST IN PATENTS | 027456 | /0154 | |
Nov 16 2015 | GAMBRO HOSPAL SCHWEIZ AG | BAXTER HEALTHCARE SA | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 037810 | /0765 |
Date | Maintenance Fee Events |
Sep 22 2006 | ASPN: Payor Number Assigned. |
Dec 29 2008 | M1551: Payment of Maintenance Fee, 4th Year, Large Entity. |
Jan 25 2013 | M1552: Payment of Maintenance Fee, 8th Year, Large Entity. |
Jan 26 2017 | M1553: Payment of Maintenance Fee, 12th Year, Large Entity. |
Date | Maintenance Schedule |
Aug 23 2008 | 4 years fee payment window open |
Feb 23 2009 | 6 months grace period start (w surcharge) |
Aug 23 2009 | patent expiry (for year 4) |
Aug 23 2011 | 2 years to revive unintentionally abandoned end. (for year 4) |
Aug 23 2012 | 8 years fee payment window open |
Feb 23 2013 | 6 months grace period start (w surcharge) |
Aug 23 2013 | patent expiry (for year 8) |
Aug 23 2015 | 2 years to revive unintentionally abandoned end. (for year 8) |
Aug 23 2016 | 12 years fee payment window open |
Feb 23 2017 | 6 months grace period start (w surcharge) |
Aug 23 2017 | patent expiry (for year 12) |
Aug 23 2019 | 2 years to revive unintentionally abandoned end. (for year 12) |